Deferred access method for uplink packet channel

ABSTRACT

The equipment and techniques disclosed herein introduce a deferred acknowledgement (DACK), in the context of a protocol for a wireless station to request and obtain access to a wireless network resource for communication of one or more data packets. Essentially, a network node, such as a wireless base station, sends the DACK instruction in response to the access request telling the requesting station that the node has heard the request but that the requesting station should defer its transmission. The requesting station need not back off and re-initiate its access request. Instead, the requesting station waits for a later acknowledgement (ACK) granting access to a resource as requested. Although the DACK provides additional signaling, this technique can still utilize a fast ACK type message, that is to say a relatively short signaling packet.

RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.10/935,236, filed Sep. 8, 2004, now U.S. Pat. No. 7,436,801 the entirecontents of each of which are hereby incorporated by reference.

TECHNICAL FIELD

The present subject matter relates to techniques and equipment toimprove access procedures, for allowing end user devices to accessresources of a packet data communication network, typically, to allowtransmission of one or more packets over a wireless uplink channel to abase station of such a network.

BACKGROUND

Recent developments in telecommunications technologies have allowedexpansion of service offerings from the ubiquitous voice telephoneservice model to include an array of packet data communication services.Packet data service offerings are rapidly migrating from narrowbandtechnologies to broadband technologies, to facilitate various multimediaapplications. This evolution of data communication technologies hasincluded a rapid development and deployment of wireless mobilecommunication networks. Carriers are now deploying wireless networktechnologies offering broadband packet data communication services.Packet data communication networks utilize various techniques to controlaccess to or to allocate scarce network resources, such as packetcommunication channels in a wireless network.

Transmission deference is the notion of withholding the transmission ofa packet over a network link until transmission conditions are morefavorable for reliable data transfer. Since often a source output datarate cannot be controlled by the system, the generated data needs to betransmitted to its peer entity within a certain predetermined timewindow interval. Data being received outside this window often isdiscarded as useless. Other times, data delay constraints are ratherrelaxed. Data again has to be transmitted within some time period, butthat period could be much longer than that of low delay constraineddata. Part of the art in communicating is to relay all sorts ofdifferent delay constrained data concurrently at maximum throughputwithout violating the data delay constraints. Obtaining a high datathroughput when operating with highly uncontrollable sources requiresbuffering and sophisticated transmission scheduling algorithms. Link ornetwork resource allocation algorithms often perform highly complexoptimization procedures in determining how to allocate link or networkresources to different users. For long-term resource utilization, enoughtime must be available for collecting resource demands, processing themand then performing the resource allocation.

In highly centrally controlled networks, a centrally located controllercontrols resource allocation; and all data transmissions are scheduledin advance. When enough time is available for carrying out theunderlying processes, these types of resource allocation mechanisms arehighly effective and tend to maximize system throughput while providingthe quality of service expected by the system users. Systems of thistype are mostly seen when the performed services are low delayconstrained, such as in voice or real time video applications. Here,strict delay constraints are imposed and enough system capacity isallocated to guarantee the required QoS. Since the time at which thevoice or video connection is actually implemented in the network is nothighly constrained, centrally located controllers have enough time toreceive a request, process it, allocate the required network resourceand inform the user that the resources have been allocated for use. Someform of central controllability provides a sense of system reliability;and unexpected or even catastrophic events can be dealt with efficientlyand effectively within a short time interval. Service providers oftennegotiate contracts with their customers, which guarantee that events ofthis type either do not happen, or their effects are kept to a minimum.

Until now, real time services have been offered over networks, whichwould guarantee their required QoS. For other types of services, datanetworks operate in parallel to offer services not requiring low delayconstraints. The best example of such a network is the Internet.Building and monitoring these different networks at all times is a hugecost, which translates to higher usage fees, albeit at the required QoS.The experience of the Internet so far is that services are notguaranteed. The resource allocation in these types of networks are moreor less non-existent, and when the system is loaded, the delay couldbecome very long thereby rendering certain applications unusable.

Other types of networks that have lately seen widespread use are localarea networks (LANs) and in particular wireless local area networks(WLANs). Here the notion of resource allocation is associated with theend user device rather than a centrally located controller, althoughcertain types of such networks do retain a level of centralcontrollability. With the end user devices becoming more intelligent,resource management has become a more distributed oriented process.Clearly, allowing a fully distributed resource allocation does haveconsiderable merits. For instance, a centrally located and expensivenode to perform resource allocation is not required. Furthermore, thedelay associated with data collection, processing and other resourcemanagement signaling functions is removed.

The differentiation of services does not stop at real time vs. non realtime services. With the proliferation of electronic devices, a varietyof different services requiring different QoS levels have beenintroduced. It is certainly not economically sensible to build adifferent network for each set of relatively dissimilar services. Amerging of different types of services onto a single network platform isrequired.

Having a single network for all services imposes a major hurdle in theresource allocation requirements. A centrally controlled system cannotrespond fast enough to accommodate changes in the network. Usage andscheduling a large number of users presenting bursty types of trafficgreatly increases the amount of signaling and control overhead,sometimes to the point that the amount of overhead is more than theamount of the transmitted data itself. Furthermore, the signaling couldbe long enough to eliminate one of the biggest advantages of centrallycontrolled systems, which is the low delay constraint of guarantee.

A distributed control communication system can respond very fast inproviding resources to different end points in a highly dynamic manner.End points are allowed to make their own measurements and decide aboutallocating (Capturing) a network resource for themselves. Clearly, thedelay for resource allocation could be made very small; and there couldbe very little if any associated signaling overhead. Clearly, if aresource is not in use, an end point entity, which needs it, should nothave to ask the network and wait for possibly a long time period to geta response back when the resource has been free all along.

Methods have been developed which tend to perform well over a largerange of network types or mixture of service usage. Methods such as pureAloha and slotted-Aloha are the pre-cursors of the large variety ofmethods that have been developed over the years. In pure-Aloha, an endpoint transmits whenever it has data. If the transmission collides witha transmission from another end point, the data is transmitted againuntil a successful transmission has occurred. There is minimal othersignaling overhead required (besides the acknowledgment of successfultransmission). The throughput of this method, however, is below 18%.This is clearly not a good system when the medium the system iscommunicating on is expensive. A slotted Aloha system maintains a timeslot discipline, where a user transmits only at the beginning of a timeslot and may hold the slot for its duration and beyond. The throughputof this approach is twice as much as for pure Aloha, but this gain isoften not substantial enough to be attractive. Both Aloha types offer nosensing of the medium before transmission.

Methods like carrier sense multiple access (CSMA) require the end pointsto perform a carrier sense by which they can determine if the medium isalready in use, before they themselves try to use it. CSMA being simpleand effective has been popularized in various existing WLAN systems. Itcan operate without a central control node, and it only requires two endpoints to set up a functional network.

Fully distributed controlled systems, however, have the drawback thatvital system resource and usage data are not available to all end pointsat all times. Each end point needs to operate based solely on the amountof information it can retrieve from sensing its environment. Having tooperate with less and often minimal information, often placesdistributed control systems at a great disadvantage. Another majorimpairment is that of absorbability. In broadly physically distributednetworks, end points cannot observe all medium activity over the fullnetwork. This limited absorbability could impose severe operationalpenalties to the overall system capacity. Methods such as RTS/CTS havebeen developed to deal with this problem often termed the “Hidden Node”problem.

Often systems need to retain a central controller. Since most smallnetworks need to interact with other larger networks, through somegateway, this gateway is a natural location for a central networkcontroller. Having a central controller could offer various advantagesto a system that otherwise uses mostly distributed control to performresource allocation. When a flavor of central control is imposed on adistributed functionality, capabilities otherwise difficult to obtainnow become readily available. A semi-autonomous resource allocationcould provide the fast speed of distributed (autonomous) systems and thereliability and information access of central control systems. Resourceallocation methods of this type are founded for example in ISMA (InhibitSense Multiple Access) systems. Here, information is relayed from thenetwork about the current use of the network resources. An end point isinhibited from accessing a resource that the network has declared asunavailable. The end points could contend for the idle or availableresources in a distributed manner.

The issues behind Distributed vs. Centralized Resource Allocation inmobile networks could be itemized as follows: In Distributed networks,a) wireless end points control their transmission themselves, b)resource allocation processes (algorithms) are simple, c) transmissionsare robust against other radio interference, d) ability to operate inad-hoc networks or when channel is shared. In Centralized Network, a) acentral controller as a Base Station is required, b) a Base Stationschedules both Uplink and Downlink transmissions, c) better control overradio resources, d) better service guarantees such as (fairness, delay,loss, etc.) e) better suited to commercial systems such as cellular andGPRS.

SUMMARY

A need exists for a semi-autonomous dynamic resource allocation schemeto accommodate the different types of services requiring differentlevels of data delay constraints. In such a scheme, an accessing endpoint or end user device (UE) should not have to undergo another roundof trying to access the network, which creates prolonged delays to theUE's transmitted data and consequently affects the overall quality ofservice offered by the Network. It would also be advantages to providean effective mechanism by which the signaling overhead on the downlinkfrom the network control node is minimized, while retaining thecapability of assigning multiple resources to concurrently accessingUEs. As a starting point to address one or more of these needs, we willintroduce the concept of a Deferred Acknowledgement (DACK) in the accessprocedure.

For example, a network node, such as a wireless base station, sends theDACK in response to an access request from a UE station telling therequesting station that the node has heard the request but that therequesting station should defer its transmission. The requesting stationneed not back off and re-initiate its access request. Instead, therequesting station waits for a later acknowledgement (ACK) grantingaccess to a resource as requested. Although the DACK provides additionalsignaling, the amount of added overhead can be relatively small, so thatthis technique can still utilize a fast ACK type message, that is to saya relatively short signaling packet.

Implementation of the deferred acknowledgement type access procedureentails processing at the UE (e.g. in a mobile station) as well asprocessing at a network node (e.g. a base station or a radio networkcontroller). Methods embodying such procedures therefore may be definedfrom the perspectives of end user devices, network nodes and/or anoverall network operation.

Hence, one method might implement an access to a wireless communicationnetwork to transmit a data packet, and such a method example might beginwith the transmission of a request message over-the-air to a node of thewireless communication network. The request message requests access to aresource of the network, for example, to allow a user's mobile stationto transmit over an uplink channel of the wireless network. The methodalso entails receiving an acknowledgement message with a deferralinstruction, and in response, deferring transmission of the data packet.A subsequently received acknowledgement message provides an instructionallowing access to the requested network resource, and in response, thedata packet is transmitted over-the-air using the requested networkresource.

Another method provides control of access to a wireless communicationnetwork for packet data communications, for example, for two requestingdevices. The method involves receiving access request messagesover-the-air from two end user communication devices. A firstacknowledgement message is sent over-the-air to both devices. This firstacknowledgement message comprises an acknowledgement of the accessrequest message from the first device and a deferred acknowledgement forthe second device. Following the first acknowledgement message, a packetdata transmission is received over-the-air from the first end usercommunication device, via a wireless communication network resourcerequested by the first end user communication device. However, thesecond device defers its transmission. Subsequently, a secondacknowledgement message is sent over-the-air to at least the second enduser communication device. The second acknowledgement message includesan acknowledgement of the request message from the second end usercommunication device and effectively allows access by that device.Following the second acknowledgement message, the network receives apacket data transmission over-the-air from the second end usercommunication device, via a wireless communication network resourcerequested by that device.

Additional objects, advantages and novel features of the examples willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing and the accompanying drawings or may be learned by productionor operation of the examples. The objects and advantages of the presentsubject matter may be realized and attained by means of themethodologies, instrumentalities and combinations particularly pointedout in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present concepts, by way of example only, not by way of limitations.In the figures, like reference numerals refer to the same or similarelements.

FIG. 1 is a signal flow diagram useful in explaining an example of anaccess procedure utilizing a deferred acknowledgement.

FIG. 2 is a functional block diagram of a simplifiedcode-division-multiple-access (CDMA) Terrestrial Radio Access Networkarchitecture, which may utilize the deferred acknowledgement technique.

FIG. 3 is a functional block diagram of a spread spectrum base stationfor use in a network of the type shown in FIG. 2.

FIG. 4 is a functional block diagram of a spread spectrum remote ormobile station for use as a UE device in a network of the type shown inFIG. 2.

FIG. 5 is a timing diagram of an exemplary acknowledgement packet.

FIG. 6 illustrates a time division multiple access structure for anuplink packet channel (UPCH).

FIG. 7 illustrates a code division multiple access structure for anuplink packet channel (UPCH).

FIG. 8 is a timing diagram for an Uplink Status Indicator Channel(USICH).

DETAILED DESCRIPTION

The various concepts disclosed herein relate to a new technique forresource allocation and management, during an access procedure in acommunication network. The method belongs to the class ofsemi-autonomous resource allocation methodologies and is mostlyindependent of technology or system configuration. When an end pointtries to capture network resources and relies on either broader controlparameters or network based information, it often fails to complete theprocess successfully. When this process requires network intervention,any interaction with the network could serve as a useful resource forfuture end-point to network interaction. One possible way is for thenetwork to acknowledge reception of the request and signal the end-pointthat its request will be served at a later time under a previouslywell-defined manner. In a sense, network resource allocation has been“deferred” to a later time and the network is bound to take furtheraction in completing the resource allocation process.

It is noted that the term “Deference” has been used in describingwireless networks to signify access contention at a later ‘deferred’time. For example, in CSMA/CA (Carrier Sense/Multiple Access/CollisionAvoidance), the end point might defer access of the medium to a latertime if the medium has been determined to be presently occupied. Thedeference time is normally obtained by choosing a time instant at randomout of a set of time instances within a time window following the lastaccess attempt. Such existing wireless network “deferred” accessmechanisms, however, are very different from the one disclosed here.

Operations here involve the introduction of a Deferred Acknowledgement(DACK) message, sent from the controlling network node (B), during theaccess procedure. In response, the end point (or user end UE) devicewill wait for the next signaling, at which time it may receive anacknowledgement or another Deferred Acknowledgement. The deferral heredoes not necessarily guarantee that network resources will in fact beallocated, rather if they do become available and other conditions aresatisfied, (such as class priority, etc.) then the resource will beeither allocated or declined. The method will be referred as DeferredTime Channel Assignment (DTCA) method. The method takes the distinctionof assignment because the network could either allocate the resourcerequested by the end point or assign a similar resource, which couldserve for the same purpose.

A number of access requests can be acknowledged at the same time (viathe same acknowledgement packet). Some accesses may be scheduledimmediately while others may be deferred to be scheduled at the next ora later scheduling instance. The Acknowledgement could come in the formof a single unique identifier for a specific ongoing access attempt. TheACK may include additional information specifying the identification ofthe access attempt as well as providing information with respect to when(time) that the UE station should transmit the packet, the channel to beused for the transmission (i.e., Channelization code along with timeslots if necessary), power control information, time alignmentinformation, etc.

Various different options could be applicable to the deference mechanismproposed here. For example, the list of scheduled and deferredsignatures might be updated in every transmission of the ACK packet(FS-UPCH). Deferred UEs do not transmit until scheduled or theirdeference becomes outdated, i.e., the T_def_max timer is expired.

The deferred acknowledgement could utilize an Uplink Status IndicatorChannel (USICH). The USICH is a channel which signals the UEs about thestatus of the uplink packet channels (“UPCH” channels). USICH istransmitted periodically. Information that may be relayed over the USICHchannel might include current activity or inactivity of all UPCHchannels. A binary indicator for each channel shall suffice in thiscase. The USICH may also carry information regarding the largestcapacity channel available. UPCH channels might be grouped in sets ofchannels having the same transmission capabilities, in which case, theUSICH would carry information about the sets rather than the individualchannels.

Another option would be for the UEs to monitor the deferred channelsignatures and refrain from using the corresponding channels unless theyare scheduled, have become outdated or USICH has declared them as idle.Another approach is for the deferred UEs to attempt to re-access on thesame code at the immediately next opportunity. In this later case, otherUEs refrain from using the same signature, and deferred UEs need notincrease their transmit power.

The methodology, although general in its scope, will be described by wayof example in the context of cellular wireless communications, where thenetwork controller could be located in the Base Station, the RadioNetwork Controller or elsewhere on the network. In such an example, theend-points are the wireless user devices distributed geographically overa possibly large area. In conjunction with the DTCA mechanism, otherprocesses and structures will play a contributing role in performing thesought resource allocation.

Reference now is made in detail to the examples illustrated in theaccompanying drawings and discussed below. FIG. 1 illustrates theprinciple of deferred acknowledgement, in accord with the presentconcepts. As shown in that simplified example, for wirelesscommunications, the network provides three downlink (DL) channels andtwo uplink (UL) channels. The two uplink channels are transmitted by UE1and UE2, respectively. All three downlink channels are transmitted fromthe same Node-B. One of the DL channels serves as anacknowledgement/assignment channel, and the other two DL channels serveas data/control channels allocated for transmission to respective UEs.

Here, the two UEs on the uplink both initiate an access phase at thesame time. During the access phase, each UE starts transmitting over therespective uplink channel at a power level, which depends on itsdistance from Node-B, other statistical factors and various presetsystems parameters. Each UE sends a series of preamble segments, whichtransmitted at increasing power levels. Each UE device continues thisramp-up of preamble segment transmission until it reaches a preamblepower level that is detectable by Node-B, and Node-B has notified thetransmitting UE that its transmitted preamble has been detected.

In FIG. 1, preamble segments from both UE1 and UE2 are detected atapproximately the same time. Assuming the two UEs are transmittingdifferent preambles, Node-B could distinctly identify their twotransmissions. Borrowing from currently existing UMTS accesstechnologies, such as random access channel (RACH) and common packetchannel (CPCH), the different preambles signify certain channel accessrequests, whose correspondence has been previously relayed to the UEs bythe network. If the access requests by the two UEs are for resourcesthat are currently available, and the DL scheduling message (denotedhere as an ACK Packet) is capable of handling the assignment of multipleUEs at the same time, Node-B could provide both the assignmentsconcurrently and wait for the next access request.

Problems arise, however, when the resources are not available and/or thesecond node (B) does not have the capability to allocate multipleresources at the same time. The concurrent assignment of multipleresources requires that enough signaling bandwidth (which translates tosystem capacity) needs to be allocated beforehand and not to be used forany other purpose. Clearly if the concurrent assignment of resourcesdoes not happen very often, useful downlink resources will be wasted.Furthermore, if the requested resources are not immediately available,resource assignment cannot happen at all. The deferred acknowledgementtechnique ameliorates these problems by providing a mechanism by whichthe Node B can assign resources to one UE and provide a deferral noticeto the other UE. A further benefit of deference is that an accessing UEinstructed to defer access will not have to undergo another round oftrying to access the network, which otherwise would create prolongeddelays to the UE's transmitted data and consequently affect the overallquality of service offered by the network.

A mechanism by which the signaling overhead on the DL is minimized whileretaining the capability of assigning multiple resources to concurrentlyaccessing UEs is disclosed here, which streamlines the channelassignment mechanism. The required signaling overheard can be kept lowby requiring different UEs to receive channel assignments at possiblydifferent times. A dynamic process will control which UE will beassigned which channel and at what time. This process is interactive,between the UEs and Node-B.

In the example of FIG. 1, upon detecting the access requests by the twoUEs, Node B determines how to allocate resources. In the example, assumethat Node B selects UE 1 to receive an immediate channel allocation,therefore the request from UE 2 is to be deferred. Node B can use anyappropriate algorithm to determine these respective assignments. Node Btransmits an ACK packet over the first downlink channel. ACK packets canbe transmitted using Multicodes (Orthogonal Parallel Codes) and multipletime slots. Of course, the ACK packets may be transmitted in othersuitable ways over the channelization used on the particular network.The transmitted ACK packet includes an ACK for the granted accessrequest, in this case providing the information for scheduling and/orenabling the access requested by UE 1. The transmitted ACK packet alsoincludes a deferred acknowledgement (DACK) message for UE 2, effectivelyinforming UE 2 that Node B heard its access request but instructing UE 2to defer transmission.

At a predetermined time after the ACK packet transmission (and thusafter the ACK to UE 1), the network element Node B transmits signalingand/or data intended for the first end user device UE 1 over theassigned downlink channel, as shown in the second line of the signalflow diagram. In response to the ACK message scheduling access, thefirst end user device UE 1 initiates its data transmission over theappropriate uplink channel, as shown in the fourth line of the signalflow diagram. However, in response to the DACK it received, the otherend user device UE 2, waits for a further ACK packet transmission.

In the simple example of FIG. 1, when the next time for an ACK packetarrives, although it is engaged in communications to/from UE 1, thenetwork element at Node B has only one unsatisfied access requestpending. Since sufficient resources are available to satisfy the requestfrom UE 2, Node B allocates those resources and sends an ACK messagecontaining scheduling information or the like for UE 2 in the second ACKpacket transmission. At a predetermined time after the second ACK packettransmission (and thus after the ACK to UE 2), the network element NodeB transmits signaling and/or data intended for end user device UE 2 overthe assigned downlink channel, as shown in the third line of the signalflow diagram. In response to the second ACK message scheduling access,the second end user device UE 2 initiates its data transmission over theappropriate uplink channel, as shown in the fifth line of the signalflow diagram. In this manner, transmissions over the uplink packetchannel (UPCH) occur in predetermined time slots. Synchronization isderived from downlink-transmitted signals.

As shown, a fast Acknowledgement (e.g. first ACK packet) stops the PowerRamp-Up during the access phase, and a number of Ramp-Up access requestscan be acknowledged at the same time (over the same acknowledgementpacket). Some accesses may be scheduled immediately while others may bedeferred to be scheduled at the next or a later scheduling instance.

The Acknowledgement could come in the form of a single unique identifierfor a specific ongoing ramp-up access. The ACK may include additionalinformation specifying the identification of the access attempt as wellas providing information with respect to when (time) that the mobilestation should transmit the packet, the channel to be used for thetransmission (i.e., Channelization code along with time slots ifnecessary), power control information, time alignment information, etc.

The order of deference may be relayed in the scheduling message(Acknowledgement Packet). For example, when three UPCH accesses areacknowledged at the same time, Acknowledged access A could be scheduledimmediately, Acknowledged Access B the next scheduling instance, andAcknowledged Access C the scheduling instance following that ofAcknowledged Access B. The scheduling order could be relayed indifferent ways. A simple way of doing that is to relay the order by theorder they are acknowledged in time. If that is not possible, in case ofmultiple codes being used, system information will be used to resolveany ambiguities.

The deferral procedures outlined above may be implemented in a varietyof wireless networks. For discussion purposes, the examples assumeimplementation in a cellular wireless network supporting packetcommunications of digital data or other forms of digital information. Tobetter appreciate such an implementation, it may be helpful to consideran example of such a network.

In a representative wireless network example (FIG. 2), thecode-division-multiple-access (CDMA) system comprises a radio networkcontroller (RNC) 11, a plurality of base stations 13 and a plurality ofmobile stations 15. In this example, Node B is implemented by one oranother of the network elements, whereas the mobile stations 15 are theUEs. FIG. 2 shows a simplified CDMA Terrestrial Radio Access networkarchitecture. The illustrated system includes a core network 9 providingtwo-way packet data communications to and from a plurality of radionetwork subsystems (RNSs) 10. Each RNS 10 includes a radio networkcontroller (RNC) 11 and a number of base stations (BSs) 13 connected tothe respective RNC 11. The RNCs 11 of several radio network subsystems10 may be interconnected, for example by the line 12. The resourceallocation functionality of Node B may be implemented in the RNC 11 orin controllers (not separately shown in FIG. 2) implemented at the basestations 13. Each base station (BS) 13 has a BS-spread-spectrumtransmitter and a BS-spread-spectrum receiver, shown as a singletransceiver (XSCV′R) system 17 for simplicity in this drawing. Each ofthe mobile stations (MS) 15 has an MS-spread-spectrum transmitter and anMS-spread-spectrum receiver (not separately shown). Exemplarytransmitters and receivers for use in the BS and MS network elements arediscussed in more detail below, with regard to FIGS. 3 and 4. Thetransceivers 17 and associated antennas at the base stations, togetherwith the transceivers and antennas in the mobile stations, provide thetwo-way signaling and data communications over the air-link, such asthose shown in FIG. 1.

In a typical embodiment, the radio network controller (RNC) 11 and corenetwork 9 provide two-way packet data communications to one or more widearea networks 19, for example a wide area packet-switched network suchas an intranet or the pubic Internet. The RNC 11 and the network 19provide the MS units 15 with two-way packet data communications servicesto enable communication to and from devices, represented by way ofexample by the IP telephone 21, the personal computer (PC) 23 and theserver 25.

The CDMA type spread-spectrum system of FIG. 2 provides a number oflogically different channels for upstream and downstream communicationsover the air-link interface. Each channel is defined by one or more ofthe codes, for example the spreading code and/or the scrambling code.Several of the channels are common channels, but most of the channelsare used for uplink or downlink packet communications between the basestations 13 and the mobile stations 15.

The RNC 11 measures traffic through the base stations 13 going to andfrom the mobile stations 15. In this way, the radio network controller(RNC) 11 monitors traffic demand in the illustrated network. The RNC 11assigns physical channel resources to the mobile stations 15, byre-configuring the state of a packet data connected mode of each mobilestation 15 within each cell of each base station 13.

In the wireless system of FIG. 2, when a mobile station 15 initiates anaccess request procedure (e.g. a RACH access), the serving base station13 can either send back an acknowledgement (ACK), a negativeacknowledgement (NACK), or the new Deferred Acknowledgement (DACK). Ifthe mobile station 15 receives an ACK, it will go ahead with the normalprocess to send its data over the uplink. If the mobile station 15receives a NACK, it will back off and restart the access requestprocedure again. The ACK and NACK operations are essentially performedas in existing proposals for 3G and 4G type wireless networks. In thepresent procedure, however, the mobile station 15 may also receive theDACK. The DACK message informs the mobile station 15 that the station'saccess request was received, and it serves to instruct the mobilestation to wait for the next round of signaling, for anotheracknowledgement/assignment instruction. The mobile station 15 willneither send its data nor back off. Instead, it will wait for the nextacknowledgement/assignment signaling packet. The mobile station 15 willrepeat this decision process again based on the kind of acknowledgement(ACK, NACK or DACK) it receives in the next round.

From the base station side, the base station 15 (or other network node,such as the RNC 11) will keep a list of outstanding requests, forexample as a waiting list, in an ordered manner. The ordering can bebased on the priority of the service requested, on a first come firstserve basis, or any other basis the system or system operator deemsappropriate. When channel resources become available for use, the basestation 15 will notify the waiting mobile station 15 to access thatresource, by sending the appropriate ACK to that station 15 over thedownlink signaling channel. The ordered list can be broadcast in everyACK signaling phase.

It is assumed that those skilled in the art are familiar with thestructure and operation of various devices and systems that may serve asthe network elements illustrated in FIG. 2. However, to insure a fullunderstanding of how one might implement the deferred acknowledgementmethodology in an actual wireless network, it may be helpful to brieflysummarize examples of the wireless transceiver elements of a basestation and a mobile station, which might be used to send and receivethe relevant signaling and data over the wireless air interface.

FIG. 3 illustrates an example of a BS spread-spectrum transmitter and aBS spread-spectrum receiver, essentially in the form of a base-bandprocessor for performing the PHY layer functions. The BS spread-spectrumtransmitter and the BS spread-spectrum receiver form one of thetransceivers 17 at a base station 13. The BS spread-spectrum receiverincludes an antenna 309 coupled to a circulator 310, a receiver radiofrequency (RF) section 311, a local oscillator 313, a quadraturedemodulator 312, and an analog-to-digital converter 314. The receiver RFsection 311 is coupled between the circulator 310 and the quadraturedemodulator 312. The quadrature demodulator is coupled to the localoscillator 313 and to the analog to digital converter 314. The output ofthe analog-to-digital converter 315 is coupled to a programmable-matchedfilter 315.

A preamble processor 316, pilot processor 317 and data-and-controlprocessor 318 are coupled to the programmable-matched filter 315. Acontroller 319 is coupled to the preamble processor 316, pilot processor317 and data-and-control processor 318. A de-interleaver 320 is coupledbetween the controller 319 and a forward-error-correction (FEC) decoder321. The decoder 321 outputs data and signaling received via any of theUL channels to the media access control “MAC” layer (not shown).

The BS spread-spectrum transmitter includes a forward-error-correction(FEC) encoder 322 coupled to an interleaver 323. A packet formatter 324is coupled to the interleaver 323 and to the controller 319. A variablegain device 325 is coupled between the packet formatter 324 and aproduct device 326. A spreading-sequence generator 327 is coupled to theproduct device 326. A digital-to-analog converter 328 is coupled betweenthe product device 328 and quadrature modulator 329. The quadraturemodulator 329 is coupled to the local oscillator 313 and a transmitterRF section 330. The transmitter RF section 330 is coupled to thecirculator 310.

The controller 319 has control links coupled to the analog-to-digitalconverter 314, the programmable-matched filter 315, the preambleprocessor 316, the digital-to-analog converter 328, the spreadingsequence generator 327, the variable gain device 325, the packetformatter 324, the de-interleaver 320, the FEC decoder 321, theinterleaver 323 and the FEC encoder 322.

These functions are well known in the art, and variations to this blockdiagram can accomplish the same functions.

A received spread-spectrum signal from antenna 309 passes throughcirculator 310 and is amplified and filtered by the receiver RF section311. The local oscillator 313 generates a local signal, which thequadrature demodulator 312 uses to demodulate in-phase and quadraturephase components of the received spread-spectrum signal. Theanalog-to-digital converter 314 converts the in-phase component and thequadrature-phase component to digital signals. The programmable-matchedfilter 315 despreads the received spread-spectrum signal components. Acorrelator, as an alternative, may be used as an equivalent means fordespreading the received spread-spectrum signal.

The preamble processor 316 detects a preamble portion of the receivedspread-spectrum signal. The pilot processor 317 detects and synchronizesto a pilot portion of the received spread-spectrum signal. The data andcontrol processor 318 detects and processes the data portion of thereceived spread-spectrum signal. Detected data passes through thecontroller 319 to the de-interleaver 320 and FEC decoder 321. Data andsignaling from the up-link are outputted from the FEC decoder 321 to thehigher layer elements in or associated with the BS 13 and through thelink to the RNC 11.

The RNC 11 supplies data and signaling over a link to the base station.In the BS transceiver, the MAC layer elements supply data and signalinginformation, intended for down-link transmission, to the input of theFEC encoder 322. The signaling and data are FEC encoded by the FECencoder 322, and interleaved by the interleaver 323. The packetformatter 324 formats data, signaling, acknowledgment signal, collisiondetection signal, pilot signal and transmitting power control (TPC)signal into appropriate packets. Each packet is outputted from thepacket formatter 324, and the packet level is amplified or attenuated bythe variable gain device 325. The packet is spread-spectrum processed bythe product device 326, with a spreading chip-sequence from thespreading-sequence generator 327. The packet is converted to an analogsignal by the digital-to-analog converter 328, and in-phase andquadrature-phase components are generated by the quadrature modulator329 using a signal from local oscillator 313. The modulated down-linkpacket is translated to a carrier frequency, filtered and amplified bythe transmitter RF section 330, and then it passes through thecirculator 310 and is radiated by antenna 309.

FIG. 4 shows an example of an MS spread-spectrum transmitter and an MSspread-spectrum receiver, essentially in the form of a base-bandprocessor for performing the PHY layer transceiver functions of an enduser device. The MS spread-spectrum transmitter and the MSspread-spectrum receiver are located at the remote or mobile station(MS) 15. The MS spread-spectrum receiver includes an antenna 409 coupledto a circulator 410, a receiver radio frequency (RF) section 411, alocal oscillator 413, a quadrature demodulator 412, and ananalog-to-digital converter 414. The receiver RF section 411 is coupledbetween the circulator 410 and the quadrature demodulator 412. Thequadrature demodulator is coupled to the local oscillator 413 and to theanalog to digital converter 414. The output of the analog-to-digitalconverter 415 is coupled to a programmable-matched filter 415.

An acknowledgment detector 416, pilot processor 417 and data-and-controlprocessor 418 are coupled to the programmable-matched filter 415. Acontroller 419 is coupled to the acknowledgment detector 416, pilotprocessor 417 and data-and-control processor 418. A de-interleaver 420is coupled between the controller 419 and a forward-error-correction(FEC) decoder 421. The decoder 421 outputs data and signaling receivedvia any of the DL channels to the MAC layer elements (not shown) of theMS.

The MS spread-spectrum transmitter includes a forward-error-correction(FEC) encoder 422 coupled to an interleaver 423. A packet formatter 424is coupled through a multiplexer 451 to the interleaver 423. The packetformatter 424 also is coupled to the controller 419. A preamblegenerator 452 and a pilot generator 453 are coupled to the multiplexer451. A variable gain device 425 is coupled between the packet formatter424 and a product device 426. A spreading-sequence generator 427 iscoupled to the product device 426. A digital-to-analog converter 428 iscoupled between the product device 428 and quadrature modulator 429. Thequadrature modulator 429 is coupled to the local oscillator 413 and atransmitter RF section 430. The transmitter RF section 430 is coupled tothe circulator 410.

The controller 419 has control links coupled to the analog-to-digitalconverter 414, the programmable-matched filter 415, the acknowledgmentdetector 416, the digital-to-analog converter 428, the spreadingsequence generator 427, the variable gain device 425, the packetformatter 424, the de-interleaver 420, the FEC decoder 421, theinterleaver 423, the FEC encoder 422, the preamble generator 452 and thepilot generator 453.

These functions are well known in the art, and variations to this blockdiagram can accomplish the same functions.

A received spread-spectrum signal from antenna 409 passes throughcirculator 410 and is amplified and filtered by the receiver RF section411. The local oscillator 413 generates a local signal, which thequadrature demodulator 412 uses to demodulate in-phase and quadraturephase components of the received spread-spectrum signal. Theanalog-to-digital converter 414 converts the in-phase component and thequadrature-phase component to digital signals. The programmable-matchedfilter 415 despreads the received spread-spectrum signal components. Acorrelator, as an alternative, may be used as an equivalent means fordespreading the received spread-spectrum signal.

The acknowledgment detector 416 detects certain acknowledgments in thereceived spread-spectrum signal. The pilot processor 417 detects andsynchronizes to a pilot portion of the received spread-spectrum signal.The data and control processor 418 detects and processes the dataportion of the received spread-spectrum signal. Detected data passesthrough the controller 419 to the de-interleaver 420 and FEC decoder421. Data and signaling from the DL are outputted from the FEC decoder421 to the higher level elements in or associated with the MS 15.

In the MS transceiver, the MAC layer elements supply data and signalinginformation intended for transmission over the up-link channel, to theinput of the FEC encoder 422. Data and signaling information are FECencoded by FEC encoder 422, and interleaved by interleaver 423. Thepreamble generator 452 generates a preamble, and the pilot generator 453generates a pilot for the preamble. The multiplexer 451 multiplexes thedata, preamble and pilot, and the packet formatter 424 formats thepreamble, pilot and data into a common-packet channel packet. Further,the packet formatter 424 formats data, signaling, acknowledgment signal,collision detection signal, pilot signal and TPC signal into a packet.The packet formatter 424 outputs the packet, and the packet level isamplified or attenuated by variable gain device 425. The packet isspread-spectrum processed by product device 426, with a spreadingchip-sequence from spreading-sequence generator 427. The packet isconverted to an analog signal by digital-to-analog converter 428, andquadrature modulator 429 using a signal from local oscillator 413generates in-phase and quadrature-phase components. The modulatedup-link packet is translated to a carrier frequency, filtered andamplified by the transmitter RF section 430 and then it passes throughthe circulator 430 and is radiated by the antenna 409.

U.S. Pat. No. 6,169,759 to Kanterakis et al. issued Jan. 2, 2001provides a more detailed description of the operation of the PHYtransceivers shown in FIGS. 3 and 4, for example in a CPCH type channeltransmission.

The uplink packet channel (UPCH), proposed here with the deferredacknowledgement, may be implemented in a manner somewhat similar to oras an enhancement to the RACH channel in the 1.28 Mcps TDD option of3GPP. The UPCH may utilize the same type of channels as in the RACH butthese channels are expanded if necessary to accommodate additionalinformation transfer as needed. It is the intent of such animplementation to remain as close to the operational requirements ofRACH as possible, but incorporate new functionalities to enhance systemaccess capabilities and system data transfer capacity. The new channelconstruct will be designed to accommodate the efficient transfer ofsmall to medium size packets on the Uplink. The delimiter of when to usea dedicated channel (DCH) when the packet to be transferred is largewill be an adjustable system parameter.

It is proposed that the UpPCH channel will still be used as an UplinkPreamble/Pilot-Tone transmission and the FPACH as the channel forsignaling the UE's the preamble detection events at Node-B andscheduling information control.

There are two main alternatives in carrying out the proposedfunctionality. The first alternative is to retain the same exactcapabilities offered by the current UpPCH and FPACH but use theextra-unused bits in FPACH to perform some of the proposedfunctionalities. The resources will need to be shared between the RACHand UPCH. This will require that the UpPCH pilot-tones be shared betweenthe RACH and UPCH on the uplink, and the FPACH will need to betime-multiplexed between RACH and UPCH. The extra bits in FPACH could beused by UPCH in the RACH time slot as well. We will call this channelFS-UPCH for Forward Signaling UPCH. The load requirements of RACH wouldbe reduced since UPCH will take off some of the RACH load. It should bepossible to eliminate RACH without substantial reduction in systemperformance.

The other alternative is to split the UpPCH resources between RACH andUPCH or redesign the UpPCH to include additional codes which then couldbe shared by RACH and UPCH. On the DL, an additional FPACH channel, callit again FS-UPCH, will be added to accommodate the DL signaling requiredfor UPCH. This channel could be easily incorporated into the system bycode multiplexing more channels, preferably in the same time slot as thecurrent FPACH. The extra resources in FPACH need not necessarily beused.

For both of the above alternatives, we propose that Closed Loop PowerControl (CLPC) is used during the packet data transfer portion of UPCH.Additional signaling during the data transmission interval will bedescribed later. Additional Associated UPCH (A-UPCH) physical channelswill be needed on the DL to accommodate the proposed CLPC and otherrequired DL signaling for the UPCH channels. A signaling channeldedicated to signal the UPCH channel availability and minimum spreadingfactor available for UPCH is proposed. This channel will be referredhere as USICH for Uplink Signaling Indicator Channel. This channel issimilar in concept to that of CPCH in the FDD mode.

The methodology or protocol for resource access, using the deferredacknowledgement technique, is implemented by elements in the mobilestation and elements in the network. The control element in the mobilestation may be the controller 419 in the baseband processor (FIG. 4)forming the mobile station transceiver or the control element may be aprogrammed processor (in the MAC or higher level element) in the mobilestation. The control element on the network side may be the controller319 in the baseband processor (FIG. 4) forming the base stationtransceiver 17 a programmed processor (higher level element) in the basestation 13 or a processor of the radio network controller 11.

It may be helpful to consider a first example of a deferredacknowledgement type access procedure, as might be implemented usingequipment such as shown in FIGS. 2-4. First a mobile station 15 randomlyselects a preamble, which represents a sub-channel from a set ofpre-allocated common channels and sends its access request. The accessrequest can be in the form of random access channel (RACH) with ramp-up,as in the example of FIG. 1, or in any other form. Upon receiving theaccess request, the base station 13 (or other element serving as Node B)examines the current usage of the requested channel. The base station 13will send out: an ACK if the channel is available, a DACK if the basestation keeps the request on its waiting list, or a NACK if it cannotaccommodate the request in the near future. The ACK, NACK and DACK cancorrespond to the selected preamble (resource type requested) ratherthan being specific to each mobile station 15. Depending on the system,these messages may also correspond to a specific mobile station if theaccess request contains an ID of the transmitting mobile station 15.

If the mobile station receives an ACK, it will go ahead to send its dataover the uplink channel corresponding to the selected preamble. If themobile station receives no acknowledgement or a “NACK,” it will back offand restart the access request procedure again at a later time. If themobile station receives a DACK, it will neither send its data nor backoff. Instead, it will wait for the next acknowledgement phase. Themobile station will repeat this decision process again based on the kindof acknowledgement it receives in the next round. This is essentiallythe operation performed by the second end user device (UE 2) in the flowof FIG. 1.

During Ramp-Up, the utilized preamble signatures could be changed whenthe signatures do not alter the type of requested UPCH channel. Channeltype shall pertain to UPCH channels according to their setclassification.

As another example, assume an ACK Packet is as shown in FIG. 5. Here, asingle UE can be assigned a resource each time an ACK-Packet istransmitted. In particular, a number of UEs can be acknowledged at thesame time but only one of them can be assigned a resource. Location A onthis figure holds the signature of the UEs to be allocated a resource,while locations B and C hold the signatures of UEs to be allocated aresource at a later time when another such ACK Packet is transmitted.The placement order of the different UE signatures in time could signifywhich UE will be assigned at what instant and the remaining ones later.

Locations E, F and G are locations, which hold signaling information forthe scheduled UE access. This signaling information could be much morein comparison to the information required to transmit a single UEsignature. For example, the scheduling message could hold the timelocation of the start of the assigned resource at some time within thenext few time frame periods to within a small fraction of a transmittedsymbol. In CDMA, transmitted symbols could be taken to be chips, whichwill require timing accuracies to within a small fraction of a chip.This time assignment is made in reference to the scheduled UEs currenttiming reception at Node-B, which in essence provides a timing alignmentof the Uplink channel to be used by the assigned UE. Other signaling,such as signaling as to which channel to use and at what power level totransmit at could also be relayed to the scheduled UE.

In case there are only two UEs to be scheduled, as shown in FIG. 1, UE 1could be scheduled with a first ACK-Packet and UE 2 with the secondACK-Packet. Here it is shown that UE 2 ceases to transmit additionalpreambles once it's been ACKed. It is left here as an option by whichUE2 could continue to transmit preambles at the same or a lower rate ofincrease of it's power until the ACK-Packet at which it will bescheduled will arrive. It is possible for the deferred UE to remain inthis state for a number of received ACK-Packets before it is scheduledto actually transmit via an assigned/requested resource. Having startedaccessing first does not guarantee being assigned first. This can easilybe done through Node-B by manipulating the time order of the UE'stransmitted signatures. As an aside, a UE signature for the purpose ofthis discussion is the preamble signature used by the UE.

The proposed method could operate on either open or closed loop powercontrol. When using open loop power control, the transmitting UEsinitially set their power levels through some predetermined mechanismand then they can adjust their transmitting power levels only by sensingthe power level of the downlink signals. In TDD systems, open loop powercontrol is a better option than it is for FDD systems. Because the samefrequency channel is used for both uplink and downlink transmissions,the power change on the downlink provides a good measure of the powerchange on the uplink. Here it is the preferred option that closed looppower control is used for UPCH, which may necessitate use of a dedicatedassociated DL channel to support Uplink Power Control. Each transmittingUE is assigned a downlink channel, which serves for controlling thepower of the uplink transmissions (see e.g. FIG. 1).

A further functionality of this associated downlink control channel willbe to provide synchronization adjustments through the SYNC portion ofthe transmission as well as other signaling control information, such asa Start of Message Indicator (SMI) and End of Transmission (EOT). TheSYNC signaling will allow uplink transmissions of different UPCHchannels to arrive at Node-B in a synchronous manner. This could then beused to make different UPCH transmission to be orthogonal to each otherby the use of orthogonal codes or symbols. Note that orthogonality hereis dependent on the amount and severity of the multipath channels theUEs are operating upon. The functionality of SMI and EOT signaling isthe same as for existing CPCH communications. Because the amount ofsignaling carried by an associated UPCH channel is relatively small,many associated CPCH channels could be transmitted during a singleframe. Each of these associated UPCHs is for controlling a differenttransmitting UE.

A Time Division Multiplexing (TDM) approach is shown in FIG. 6, while aCode Division Multiplexing (CDM) approach is shown in FIG. 7. Note thatfor TDD systems, a Midable is normally used in the middle of each frame.Clearly, in cases where very small rate channels can be assigned, CDMmight be the preferred approach, otherwise the TDM approach should beused. As is the case of CSICH of CPCH, a similar functionality could beimplemented for UPCH.

In FIG. 8, a UPCH Status Indicator Channel (USICH) is shown. Thischannel is normally a slow rate channel and could span a number of timeslots. Time Division or Code Division Multiplexing with ACK-Packetscould reduce the overhead resource cost of this channel.

It may be helpful to consider another example of the deferredacknowledgement which uses a Group Channel Request (Single Group). Inthis example, a UE mobile station 15 randomly selects a preamble, whichrepresents a group of sub-channels of the common channel and sends itsaccess request (e.g. Group A consisting of sub-channels 1 to 5). Uponreceiving the access request, the base station 13 (or other networkelement serving as Node B) examines the current usage of the requestedgroup of channels. The base station 13 will send out: an ACK if thechannel is available, a DACK if the base station keeps the request onits waiting list, or a NACK if it cannot accommodate the request in thenear future.

When the base station sends an ACK message, the ACK message will specifythe channel within the group of requested channels through which themobile station 15 is authorized to send its data. In a TDD system, theACK message will also carry timing information and other informationpertaining to the TDD system. If the mobile station 15 receives an ACK,it will go ahead to send its data as instructed. If the mobile stationreceives a No-ACK or NACK, it will back off and restart the accessrequest procedure again at a later time. If the mobile station 15receives a DACK, it will neither send its data nor back off. Instead, itwill wait for the next acknowledgement message. The mobile station willrepeat this decision process again based on the kind of acknowledgementit receives in the next round.

Another example of the deferred acknowledgement uses a ChannelAssignment technique. Again, the mobile station 15 randomly selects apreamble, but here, the selected preamble does NOT represent anyspecific one or group of sub-channels of a common channel. The preambleis purely for collision reduction purpose. The mobile station sends thepreamble in its access request, to the base station. Upon receiving theaccess request, the base station 13 examines the current usage of theall common channels. The base station 13 will send out: an ACK if thechannel is available, a DACK if the base station keeps the request onits waiting list, or a NACK if it cannot accommodate the request in thenear future. When the base station sends an ACK message, the ACK messagewill specify the channel (channel assignment) through which the mobilestation shall send its data. In a TDD system, the ACK will also carrytiming information and other information pertaining to the TDD system.If the mobile station 15 receives an ACK, it will send its data throughthe channel specified by the ACK. If the mobile station receives aNo-ACK or NACK, it will back off and restart the access requestprocedure again at a later time. If the mobile station receives a DACK,it will neither send its data nor back off. Instead, it will wait forthe next acknowledgement. The mobile station will repeat this decisionprocess again based on the kind of acknowledgement it receives in thenext round.

The deferred acknowledgement techniques, such as outlined in the aboveexamples, may be used together with a number communication features. Oneexample of such an optional feature relates to Broadcast ChannelAvailability. With this additional feature, the base station 13broadcasts the availability on an UPCH Status Indicator Channel (USICH)status, and capacity of each or a group of common channels. Mobilestations trying to request access monitor the USICH and refrain fromusing the unavailable signatures (preambles) unless they have becomeoutdated or until the data in the USICH has declared the signatures(preambles) as idle.

Another optional feature utilizes Ordered List Information. Here, thebase station 13 would include the ordered list (waiting list)information in its DACK message every round of ACK packet transmission.The mobile stations trying to request access monitor the deferredsignatures and refrain from using them unless they are scheduled, havebecome outdated or the USICH has declared them as idle. As a furthervariant, the mobile stations that requested access and have received aDACK might also keep a maximum deferral timer T_def_max. In that case,deferred stations would not transmit until scheduled or their T_def_maxhas expired. Alternately, the mobile stations that received a DACK andkeep a maximum deferral timer T_def_max might exit the waiting list whentheir T_def_max has expired. Essentially, the deferred UE would considerits deference invalid if it is not scheduled within T_def_max secondsafter its actual or perceived deference instance. In the examplesdiscussed above, it is possible to schedule one UE for access duringeach cycle. In other implementations, it is also possible to schedulemore than one UE with a single DACK. In the later case, the DACK messageincludes Scheduling Information for multiple UEs.

The deferred acknowledgement techniques may also be implemented with avariety of other features, such as closed loop power control duringmessage transmission. As another feature example, additional controlsignaling could be applied on the Uplink and Downlink, to in enhance thetransmission flexibility and thus system capacity. Such additionalcontrol signaling might include Transport Format Combination Indicators(TFCI), Fine Uplink Synchronization Control (FUSC), Uplink and DownlinkAntenna Control, Adaptive Modulation and Coding signaling (AMCS), etc.Power Control and other control signaling information could betransmitted over a single or multiple time slots in a Time DivisionMultiple Access (TDMA) manner. Alternatively, Power Control and othercontrol signaling information could be transmitted over a single ormultiple time slots in a Code Division Multiple Access (CDMA) manner.The number of time slots and the number of transport packets to betransmitted per access could be predetermined for all possible UPCHtransmissions.

Another feature that may be useful is a Start of Message Indicator(SMI), similar to that of the CPCH in the FDD option. The SMI may beused on the downlink to remove unwanted uplink transmissions. A UE mightfalsely determine that it is scheduled for transmission, or it wasscheduled for transmission but had falsely determined the code totransmit at (channel). A UE, which does not hear a proper SMI, that isan SMI transmitted over the expected DL channel (A-UPCH), shoulddiscontinue transmission and attempt another access at a later timeinstant. An appropriate SMI functionality is disclosed in more detail incommonly assigned U.S. Pat. No. 6,507,601 to Parsa et al. entitled“Collision Avoidance,” the disclosure of which is incorporated entirelyherein by reference.

In a similar fashion, it may be desirable to add an End of Transmission(EoT) message. The EOT is sent over the paired A-UPCH. This message willforce a transmitting UE to terminate its current ongoing transmission.As another option, an End-of-Message (EoM) indicator could provide asignal to Node-B that the UE has completed its message transmissionbefore reaching the end of its pre-allocated transmission interval.

Also, additional packets might be piggy-backed during a transmission ifthe pre-allocated message duration has not expired and additionalpackets have arrived for transmission. It may also be desirable to addCollision Resolution. In this case, two or more UEs transmit at the sametime in the same channel, Node-B if able to detect their presence, coulddemodulate all of them by setting the DL power control signaling tooscillate between up and down commands, which virtually sets the TPCoff.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that they may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim any and allmodifications and variations that fall within the true scope of thepresent concepts.

1. A mobile station, comprising: a spread-spectrum transmitter; aspread-spectrum receiver; and a controller coupled to thespread-spectrum transmitter and the spread-spectrum receiver, forcontrolling operations of the mobile station for accessing a wirelesscommunication network to transmit a data packet, including operationscomprising: (a) transmitting a request message over-the-air to a node ofthe wireless communication network, the request message requestingaccess to a resource of the network, wherein the operation oftransmitting the request message comprises transmitting a sequence ofpreamble segments at sequentially increasing power levels; (b) receivinga first acknowledgement message over-the-air from the node, the firstacknowledgement message comprising a deferral instruction, and ceasingtransmission of the preamble segments in response to the receipt of thefirst acknowledgement message; (c) in response to the deferralinstruction, deferring transmission of the data packet, wherein thereare no further transmissions of preamble segments during the deferringof the transmission of the data packet; (d) receiving a secondacknowledgement message over-the-air from the node, the secondacknowledgement message comprising an instruction allowing access to therequested network resource; and (e) in response to the instructionallowing access, transmitting the data packet over-the-air using therequested network resource.
 2. The mobile station of claim 1, whereinthe instruction in the second acknowledgement message identifies aspecific channel resource of the wireless communication networkallocated from among a group of channel resources of the wirelesscommunication network.
 3. A mobile station, comprising: aspread-spectrum transmitter; a spread-spectrum receiver; and acontroller coupled to the spread-spectrum transmitter and thespread-spectrum receiver, for controlling operations of the mobilestation for accessing a wireless communication network to transmit adata packet, including operations comprising: (a) transmitting a requestmessage over-the-air to a node of the wireless communication network,the request message requesting access to a resource of the network,wherein the request message identifies a specific channel resource ofthe wireless communication network; (b) receiving a firstacknowledgement message over-the-air from the node, the firstacknowledgement message comprising a deferral instruction; (c) inresponse to the deferral instruction deferring transmission of the datapacket; (d) receiving a second acknowledgement message over-the-air fromthe node, the second acknowledgement message comprising an instructionallowing access to the requested network resource, wherein theinstruction in the second acknowledgement message allows access to thespecific channel resource of the wireless communication network; and (e)in response to the instruction allowing access, transmitting the datapacket over-the-air using the requested network resource.
 4. The mobilestation of claim 3, wherein the instruction in the secondacknowledgement message identifies a specific channel resource of thewireless communication network allocated from among a group of channelresources of the wireless communication network.
 5. A mobile station,comprising: a spread-spectrum transmitter; a spread-spectrum receiver;and a controller coupled to the spread-spectrum transmitter and thespread-spectrum receiver, for controlling operations of the mobilestation for accessing a wireless communication network to transmit adata packet, including operations comprising: (a) transmitting a requestmessage over-the-air to a node of the wireless communication network,the request message requesting access to a resource of the network,wherein the request message identifies the group of channel resources ofthe wireless communication network and requests access to the identifiedgroup of channel resources; (b) receiving a first acknowledgementmessage over-the-air from the node, the first acknowledgement messagecomprising a deferral instruction; (c) in response to the deferralinstruction, deferring transmission of the data packet; (d) receiving asecond acknowledgement message over-the-air from the node, the secondacknowledgement message comprising an instruction allowing access to therequested network resource, wherein the instruction in the secondacknowledgement message identifies a specific channel resource of thewireless communication network allocated from among a group of channelresources of the wireless communication network; and (e) in response tothe instruction allowing access, transmitting the data packetover-the-air using the requested network resource.